Diamond charged cutting tool bit



Apfili 18, 1933. 5 L. HQYT 1,904,049

DIAMOND CHARGED CUTTING TOOL BIT Filed Sept. 5, 1929 Inventor: Q SamuelLfiqgt,

UNITED STATES PATENT OFFICE smear. L. non, or scnmmc'ranr, new roax,ASSIGNOR To GENERAL comm, a CORPORATION or NEW YORK DIAMOND CHARGEDCUTTING TOOL IBI'I" ELECTRIC Application filed September 5, 1029. SerialNo. 390,621. I

The present invention relates to cutting or abrasive tool bits in whichminute diamonds or other abrasive particles are held or embedded in amatrix consisting ofa sintered,

hard, metal composition of the character described in Schroter PatentsNo. 1,549,615 and No. 1,721,416. A tool bit of this general charter isdescribedin the copending application. of George F. Taylor; Serial No.357,536, filed A ril 23, 1929.

t is one of the objects of my invention to provide an improved form oftool bit of the type described in the Taylor application. The processfor making my improved tool bit is claimed in my divisional applicationSerial sufficient to form a supporting member of desired proportions isplaced on the plunger 2. ressureis applied to the mixed vpowderedmaterials to compact them slightly into the mass 6. An upper end portionof the compacted mass is then cut away or removed and a mixture 70fsmall diamond particles or. dust, tungsten'carbide and cobalt, in theproportion of about one part by'weight diamond powder'to about to 13parts by weight of tungsten carbide and cobalt is placed in the cut awayportion of the supporting member or mass 6. This diamond chargedmaterial is sli htly compressed until its upper surface is-su tantially"alignment with the upper surface of the supporting member 6. A'layer 8consisting of tungsten carbide and cobalt about 1 3- thick is placed ontop of the sup porting member 6 and the diamond charged material 7, asindicated in Fig. 1, and pressure equal to about 1000 pounds per squareinch is applied to the materials while they are simultaneously heated toa temperature in f the neighborhood of 1350 C.," the latter being thesintering temperature of the tungsten carbide and cobalt com osition.

The layer 8 protects the diamond charged material from deteriorationduring the pressing operation. It forms a hard thin brittle Skll'l onthe top of'the tool bit. This skin is N 0., 493,815,,filed November 6,1930. According to my invention, small diamond particles are mixed witha composition of tungsten carbide and cobalt, the latter compositionbeing similar to that disclosed in the above Schroter patents. Thismixture, or dia-' mond charged material, is secured to a suportingmember consisting of tungsten carh' which will pres- 1de and cobalt in amanner ,ently be described. The combined supporting member and diamondcharged member form a tool bit which may be brazed or welded orotherwise secured to a suitable tool shank, the diamond charged materialforming the cutting portion of the tool bit.

- The novel features which I believe to be to so producing thecharacteristic of my invention are set forth with particularity in theappended claims. The invention itself however will best be understoodfrom reference to the following spec ification when considered inconnection with the accompanying drawing in which Fig. 1

shows diagrammatically a perspective view,

partly in section, of a carbon mold employed in carrying out myinvention, .while Fig. 21s a perspective view of a tool bit formed inaccordance with my invention.

Referring more particularly to the drawmg, I have indicated at 1 ahollow carbon mold fitted with oppositely disposed carbon plungers 2 and3 to which electrical conduc-' to'rs 4 and 5 may be secured in anysuitable tungsten carbide and manner. A mixtureof proportion of about13% cobalt tungsten carbide and, in an amount later removed by indingtool bit shown .in 2. T

e provision of the layer 8 avoids'the necessity of cutting away anyportion of the more expensive diamond charged material.

The finished tool bit may be welded or secured in any suitable manner toa tool shank.

Thetsupporting member 6 is cemented tungsten carbide, i. e the cobaltacts as a cement I for the tungsten carbide particles. The supportingmember itself is almost as. hard as a diamond but in the presentinstance it acts as the cementing or hinder agent for thediamond'particles.

The cemented tungsten carbide is particularly adapted for use 'asasu'pport member since it has thesame pressing, shrinking'and sinteringcharacteristics as the diamond cha material. The cemented tungstencarbide, furthermore, has sufficient strength to act as a-support memberand doesnot adversely aflect the composition of diamond charged materialat the: high temperature employed in the'hot pressing process;

5 The amount of tungsten carbide and cobalt employed in the supportingmember 6 is substantially identical with the amount of tung sten carbideand cobalt employed the surface layer 8, i'. e., the cobalt varies froma1 fewnper cent to about 25%, the remainder being tungsten carbide.

The diamond particles may vary in size depending upon the work-to beperformed but should be as large or larger than the par- 1 ticles of thecemented tungsten carbide matrix in which they are embedded. It will befound that diamond dust or powder which will pass a 40 to 100 meshwill'give satisfactory results.

What I claim as new anddesire to secure by Letters Patent oi the UnitedStates is:

1; A cutting tool bit consisting of a supporting portion and a cuttingportion, said supporting portion'being sintered and con-; sistmg largelyof tungsten carbide but containing an appreciable amount of cobalt, saidcutting portion consisting of diamond particles held .in a matrix havingsubstantially the composition'of thesupporting portion of the tool.

2. A cutting tool'bit'consisting of asintered support and a cuttingportion, said cutting portion consisting of diamond particles held ina'matrix consisting largely of a 85 cemented carbide. v I

3. A cutting tool bit consisting of a sintered support and a cuttingportion, said cutting portion consisting of diamond particles 'eld in amatrix consisting largely oi l0 a'eemented tungsten carbide.

4. A cutting tool bit consisting of a sintered support {and a cuttingportion, said cuttin portion consisting o diamond-particles eld in asintered matrix. a

(l 5. A'cu'ttin =:tool b 't adapted to be secured to a tool shan saidbit comprising a cutting portion and a supporting portion, thesupporting oo'rtion consisting substantially of a V cemented carbide,the cutting portion of said tool consisting 'of-a cemented carbidehaving abrasive part cles distributed therethrough.

r 6, A cutting toolbit adapted to be secured to a "tool shank, said bitcomprising a cut=' ting portion and a supporting portion, the

supporting portion consisting substantially of a cemented carbide com"tion, said cutt' portion containing a at one part by weight of abrasiveparticles and about 10 to g 13 arts by we' ht ot a cemented carbide.

Y witness w ereof, I" hare hereunto set my hand this 4th da ofSeptember, 1929..

